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Force motion blur problem with upper field.

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Andrés Borghi
Force motion blur problem with upper field.
on Aug 20, 2011 at 10:00:00 pm

Hi!
I'm making a comp where there is some accelerated video footage. To disimulate this and make it look like it is not accelerated I added CC force motion blur to the video.
it works perfect but when I export it, the export somehow turns the force motion blur effect off.
I tried it by adding an adjustment layer on top of the footage with the effect and also by adding it individually to every layer, but still it dissaperas in the render.
I came to notice that this only happens when i set the export to have the upper fild first. if it put it in progressive the effect works.
What can i do? since i need the exported footage to have upper field to match the rest of the film?


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ben g unguren
Re: Force motion blur problem with upper field.
on Aug 21, 2011 at 12:43:13 am

Assuming you're working in NTSC: render your animation at 60fps, then reimport it into AE, drop it in it's own comp, change the frame rate to 30 and render with fields.

For PAL you'd render at 50, then fields at 25.
(Or with drop frame NTSC it's 59.98, then 29.97, etc)

That's a weird error, by the way. Never heard of it before. But, then again, never tried it before, so....

Ben Unguren
Motion Graphics & Editing
http://www.mostlydocumentary.com


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Andrés Borghi
Re: Force motion blur problem with upper field.
on Aug 21, 2011 at 3:03:02 am

I'm in PAL so I exported it at 50 and progressive.
weirdly enough, the effect was oof this time aswell.
looks like it dissaperas when i set field dominance (not progressive) and even wehn i change the framerate.
Must be some weird bug in the effect.


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Kevin Camp
Re: Force motion blur problem with upper field.
on Aug 21, 2011 at 4:06:04 pm

It sounds like you are just using force motion blur to blend frames... You might try using frame blending (frame mix) and see if it works for you.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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Andrés Borghi
Re: Force motion blur problem with upper field.
on Aug 21, 2011 at 11:49:01 pm

I tried that, but the frame blending only works for slowed footage. when I apply it to accelered footage it doesnt change a thing. That's why i use the force motion blur fx, to simulate that objects are moving at a faster speed and to hide the fact that it is accelerated.


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Jens Enqvist
Re: Force motion blur problem with upper field.
on Aug 22, 2011 at 6:56:32 am

We are looking into this. Please contact us at support cycorefx.com



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Andrés Borghi
Re: Force motion blur problem with upper field.
on Aug 22, 2011 at 5:17:02 pm

ok!


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Jens Enqvist
Re: Force motion blur problem with upper field.
on Aug 25, 2011 at 9:54:15 am

Ok I have tried to reproduce this with both the bundled version and the HD version but can not reproduce this.
The only way I can see the effect not producing anything is if I use 50 fps footage (which is correct since interlaced frames in PAL is 50fps as well).
What framerate does your progressive footage have?

An alternative method could be to use CC Wide Time on the source footage instead.



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Andrés Borghi
Re: Force motion blur problem with upper field.
on Aug 25, 2011 at 3:55:54 pm

The original footage runs at 25 fps with upper field dominance. So, i'm making the export look just the same.
I mentioned progressive footage cause i founf put that exporting in progressive keeps the effect there. I haven't tried to revert the filed dominance in the export. like setting lower field. but that isn't gonna help since I need it in upper.


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Jens Enqvist
Re: Force motion blur problem with upper field.
on Aug 26, 2011 at 9:54:36 am

When you say "... some accelerated video footage." what exactly do you mean?
Force Motion Blur does not synthesize motion blur, it blends intermediate frames into a single frame to generate the motion blur. If your source footage does not contain any intermediate frames then there will not be any effect. What you are seeing on progressive frames (eg. comp window) is most likely the deinterlaced fields being blended. When you then render interlaced there won't be any further intermediate frames and thus no effect.
If you footage does not contain the necessary intermediate frames you may use AEs (CS5 or higher) high quality frame blending to provide synthesized frames for Force Motion Blur to use but it must then be applied as an adjustment layer.



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Andrés Borghi
Re: Force motion blur problem with upper field.
on Aug 26, 2011 at 5:48:38 pm

That's iteresting.
yes, I actually don't know how the effect works.
what I mean with accelerated footage is video footage set to last half it's duration. So, it's speed is doubled. If it's a guy running then he runs faster. But when you do just that you can tell he is not really running at that speed cause he has less motion blur than he should have if the footage was naturally like that. So using CC Force motion blur over that layer adds the amount of MB it should have making it more natural to the eye. I've checked and works both ways: using the effect in the layer and also in a adjustment layer.

When Kevin suggested using frame blending I tried that. It didn't make any result in the footage. It was the same if the FB icon was on or off. We can tell that it works with footage slowed down on AE, but when it's made to last less time it doesn't seem to do a thing.

so, that's the problem basically. I accelerated footage on my composition and want to make it look like it was filmed at that speed by adding motion blur.


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Andrés Borghi
Re: Force motion blur problem with upper field.
on Aug 26, 2011 at 5:51:19 pm

Just something I forgot to add: I'm not a native english speaker so maybe I don't know some important words that makes it easy to understand me. So, sorry in advance!


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Andrés Borghi
Re: Force motion blur problem with upper field.
on Aug 26, 2011 at 5:55:37 pm

Sorry to triple post!

Jens: What you're saying is that there's an effect that does that from AE cs5?


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Jens Enqvist
Re: Force motion blur problem with upper field.
on Aug 26, 2011 at 10:37:06 pm

Andrés, I meant that as of CS5, AE can synthesize intermediate frames so that effects such as CC Force Motion Blur or CC Wide Time can generate more graphics from less input, which is a really great improvement. :) (Thank you Adobe!)



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Jens Enqvist
Re: Force motion blur problem with upper field.
on Aug 26, 2011 at 11:17:02 pm

No worries Andrés, english is not my first language either. I just hope that my mumbling can be of some assistance!
Cheers,
-jens



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Jens Enqvist
Re: Force motion blur problem with upper field.
on Aug 26, 2011 at 11:13:36 pm

Ok, I just tried this exact thing and it worked fine, as long as I set Shutter Angle to 360. Actually setting it to 180.1 should do the job as well. There could be a rounding problem if you scale 50 fps by 50 % you might end up with 25.0001%, which is (sliiiiightly) less than 25 percent.
Try setting your shutter angle at 361 degrees, then you won't have to worry about additional frames not showing up.
I repeat my suggestion to use CC Wide Time insead. It would only require a setting relative to your speedup of the source footage. 50% would be 1 frame before and 1 frame behind.

-jens



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Jens Enqvist
Re: Force motion blur problem with upper field.
on Aug 27, 2011 at 2:21:27 am

Since you are using 50&, the CC Wide Time should actually work just a well (or easier), as just as it is applied to the pre-strecteded actual footage.
Cheer,
jens



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Andrés Borghi
Re: Force motion blur problem with upper field.
on Aug 30, 2011 at 1:44:29 am

It finally worked!
I set the shutter in the effect at 181º and the effect showed in the render.

thanks! :)


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Jens Enqvist
Re: Force motion blur problem with upper field.
on Aug 30, 2011 at 6:06:03 am

Great! Happy it worked out for you :)



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